Typical electrical connectors comprise a connector base made of an insulating material, such as plastic, for example. A plurality of electrical contacts are retained in the connector base. In a so-called “grid array” connector, the contacts are arranged in an array. Such connectors typically include contacts that are retained in the base by virtue of respective retention members that deform the insulating material when the contact is pressed into the base.
FIG. 1 depicts a pair of typical prior art contacts 10 retained in a connector base 14. Each contact 10 has a retention member 12. Retention members 12 as depicted in FIG. 1 are often referred to as “barbs.” When a contact 10 is pressed into the connector base 14, the retention member 12 deforms a wall W of the base 14. For example, the retention member 12 may penetrate the material from which the base 14 is formed. Thus, the contact 10 is retained in the base 14.
The impedance, Z, between adjacent contacts 10 is a function of the proximity of the contacts to one another. The use of retention members such as barbs 12, however, tends to create a so-called “impedance discontinuity” in proximity to the barb 12. That is, the impedance Z1 between adjacent contacts 10 as measured in proximity to the barb 12 is significantly different from the nominal impedance Z0 between adjacent contacts 10 as measured elsewhere along the length L1 of the portion of the contact 10 that is in the base 14 (along the x-direction as shown in FIG. 1).
FIG. 2 is a plot of impedance Z between adjacent prior art contacts 10, such as those depicted in FIG. 1. As shown in FIG. 2, a nominal impedance Z0 exists along most of the length L of the portion of the contact 10 that is in the base 14. In proximity to the barb 12, however, the impedance Z between the contacts 10 drops to Z1, where Z1<Z0. (The magnitude of the impedance discontinuity depicted in FIG. 2 is exaggerated for the purpose of explanation.)
Usually, such an impedance discontinuity is not significant enough to adversely affect the performance of the connector. As connector speeds increase into the range of about 10 Gbps and beyond, however, the discontinuity may adversely affect performance. To compound the problem, the demand for smaller connectors has required connector manufacturers to provide connectors with increasingly greater contact densities. Thus, adjacent contacts are nearer to one another. In such high speed, high density connectors, uniform impedance between adjacent contacts becomes ever more important.
It would be advantageous, therefore, to manufacturers and users of such high speed, high density connectors if there were available electrical contacts that could be adequately retained in the connector base, while maintaining an impedance profile (i.e., impedance between adjacent contacts as measured along the lengths of the portions of the contacts that are in the base) that is generally uniform (i.e., nearly constant) along the lengths of the portions of the contacts that are in the base.